This is a proof of concept of a bug found when using Boost/Beast HTTP features on Windows building with MSVC.

System requirements

• Microsoft Visual Studio 2019 or 2017
  • Workloads
    • Desktop development with C++
  • Individual components
    • Compilers, build tools and runtimes
      • MSVC v141 - VS 2017 C++ x64/x86 build tools (v14.16)
      • (Optional) MSVC v140 - VS 2015 C++ build tools (v14.00)
      • (Optional) MSVC v142 - VS 2019 C++ x64/x86 build tools (v14.23)
    • SDKs, libraries and frameworks
      • Windows 10 SDK (10.0.18362.0)

Steps to reproduce

1. Clone this repository.
2. Open BeastHttpSyncCrash.sln.
3. Build the solution for Release|x86.
   Some projects may fail if the optional compiler collections are not installed. Those can be ignored.
4. Run project Vc141Boost171.

Expected behavior

Program runs and exits silently

Actual behavior

Program crashes with the following exception:

Vc141Boost171.exe has triggered a breakpoint.

Source:

packages\boost.1.71.0.0\lib\native\include\boost\beast\core\impl\buffers_cat.hpp

Stack trace

Vc141Boost171.exe!boost::beast::buffers_cat_view<boost::beast::detail::buffers_ref<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::basic_fields<std::allocator<char>>::writer::field_range,boost::beast::http::chunk_crlf>>,boost::asio::const_buffer>::const_iterator::increment::operator()(std::integral_constant<unsigned int,3> __formal) Line 269	C++
  [Inline Frame] Vc141Boost171.exe!boost::mp11::detail::mp_with_index_impl_<4>::call(unsigned int) Line 114	C++
  [Inline Frame] Vc141Boost171.exe!boost::mp11::mp_with_index(unsigned int) Line 382	C++
  Vc141Boost171.exe!boost::beast::buffers_cat_view<boost::beast::detail::buffers_ref<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::basic_fields<std::allocator<char>>::writer::field_range,boost::beast::http::chunk_crlf>>,boost::asio::const_buffer>::const_iterator::operator++() Line 396	C++
  [Inline Frame] Vc141Boost171.exe!boost::beast::buffers_suffix<boost::beast::buffers_cat_view<boost::beast::detail::buffers_ref<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::basic_fields<std::allocator<char>>::writer::field_range,boost::beast::http::chunk_crlf>>,boost::asio::const_buffer>>::const_iterator::operator++() Line 84	C++
  [Inline Frame] Vc141Boost171.exe!boost::beast::buffers_suffix<boost::beast::buffers_cat_view<boost::beast::detail::buffers_ref<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::basic_fields<std::allocator<char>>::writer::field_range,boost::beast::http::chunk_crlf>>,boost::asio::const_buffer>>::const_iterator::operator++(int) Line 92	C++
  Vc141Boost171.exe!boost::beast::buffers_prefix_view<boost::beast::buffers_suffix<boost::beast::buffers_cat_view<boost::beast::detail::buffers_ref<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::basic_fields<std::allocator<char>>::writer::field_range,boost::beast::http::chunk_crlf>>,boost::asio::const_buffer>> const &>::setup(unsigned int size) Line 153	C++
  [Inline Frame] Vc141Boost171.exe!boost::beast::buffers_prefix_view<boost::beast::buffers_suffix<boost::beast::buffers_cat_view<boost::beast::detail::buffers_ref<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::basic_fields<std::allocator<char>>::writer::field_range,boost::beast::http::chunk_crlf>>,boost::asio::const_buffer>> const &>::{ctor}(unsigned int) Line 216	C++
  [Inline Frame] Vc141Boost171.exe!boost::beast::detail::variant<boost::beast::buffers_prefix_view<boost::beast::buffers_suffix<boost::beast::detail::buffers_ref<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::basic_fields<std::allocator<char>>::writer::field_range,boost::beast::http::chunk_crlf>>> const &>,boost::beast::buffers_prefix_view<boost::beast::buffers_suffix<boost::beast::buffers_cat_view<boost::beast::detail::buffers_ref<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::basic_fields<std::allocator<char>>::writer::field_range,boost::beast::http::chunk_crlf>>,boost::asio::const_buffer>> const &>,boost::beast::buffers_prefix_view<boost::beast::buffers_suffix<boost::asio::const_buffer> const &>,boost::beast::buffers_prefix_view<boost::beast::buffers_suffix<boost::beast::buffers_cat_view<boost::beast::detail::buffers_ref<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::basic_fields<std::allocator<char>>::writer::field_range,boost::beast::http::chunk_crlf>>,boost::beast::http::detail::chunk_size,boost::asio::const_buffer,boost::beast::http::chunk_crlf,boost::asio::const_buffer,boost::beast::http::chunk_crlf>> const &>,boost::beast::buffers_prefix_view<boost::beast::buffers_suffix<boost::beast::buffers_cat_view<boost::beast::http::detail::chunk_size,boost::asio::const_buffer,boost::beast::http::chunk_crlf,boost::asio::const_buffer,boost::beast::http::chunk_crlf>> const &>,boost::beast::buffers_prefix_view<boost::beast::buffers_suffix<boost::beast::buffers_cat_view<boost::beast::http::detail::chunk_size,boost::asio::const_buffer,boost::beast::http::chunk_crlf,boost::asio::const_buffer,boost::beast::http::chunk_crlf,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::chunk_crlf>> const &>,boost::beast::buffers_prefix_view<boost::beast::buffers_suffix<boost::beast::buffers_cat_view<boost::beast::detail::buffers_ref<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::basic_fields<std::allocator<char>>::writer::field_range,boost::beast::http::chunk_crlf>>,boost::beast::http::detail::chunk_size,boost::asio::const_buffer,boost::beast::http::chunk_crlf,boost::asio::const_buffer,boost::beast::http::chunk_crlf,boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::chunk_crlf>> const &>,boost::beast::buffers_prefix_view<boost::beast::buffers_suffix<boost::beast::buffers_cat_view<boost::asio::const_buffer,boost::asio::const_buffer,boost::beast::http::chunk_crlf>> const &>>::emplace(unsigned int &) Line 199	C++
  Vc141Boost171.exe!boost::beast::http::serializer<1,boost::beast::http::basic_string_body<char,std::char_traits<char>,std::allocator<char>>,boost::beast::http::basic_fields<std::allocator<char>>>::do_visit<2,boost::beast::http::detail::write_some_lambda<boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy>>>(boost::system::error_code & ec, boost::beast::http::detail::write_some_lambda<boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy>> & visit) Line 52	C++
  Vc141Boost171.exe!boost::beast::http::serializer<1,boost::beast::http::basic_string_body<char,std::char_traits<char>,std::allocator<char>>,boost::beast::http::basic_fields<std::allocator<char>>>::next<boost::beast::http::detail::write_some_lambda<boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy>> &>(boost::system::error_code & ec, boost::beast::http::detail::write_some_lambda<boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy>> & visit) Line 111	C++
  [Inline Frame] Vc141Boost171.exe!boost::beast::http::detail::write_some_impl(boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy> &) Line 452	C++
  [Inline Frame] Vc141Boost171.exe!boost::beast::http::write_some(boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy> &) Line 523	C++
  Vc141Boost171.exe!boost::beast::http::write<boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy>,1,boost::beast::http::basic_string_body<char,std::char_traits<char>,std::allocator<char>>,boost::beast::http::basic_fields<std::allocator<char>>>(boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy> & stream, boost::beast::http::serializer<1,boost::beast::http::basic_string_body<char,std::char_traits<char>,std::allocator<char>>,boost::beast::http::basic_fields<std::allocator<char>>> & sr, boost::system::error_code & ec) Line 671	C++
  [Inline Frame] Vc141Boost171.exe!boost::beast::http::write(boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy> &) Line 798	C++
  Vc141Boost171.exe!boost::beast::http::write<boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy>,1,boost::beast::http::basic_string_body<char,std::char_traits<char>,std::allocator<char>>,boost::beast::http::basic_fields<std::allocator<char>>>(boost::beast::basic_stream<boost::asio::ip::tcp,boost::asio::executor,boost::beast::unlimited_rate_policy> & stream, const boost::beast::http::message<1,boost::beast::http::basic_string_body<char,std::char_traits<char>,std::allocator<char>>,boost::beast::http::basic_fields<std::allocator<char>>> & msg) Line 753	C++
  Vc141Boost171.exe!main() Line 33	C++
  [Inline Frame] Vc141Boost171.exe!invoke_main() Line 78	C++
  Vc141Boost171.exe!__scrt_common_main_seh() Line 288	C++
  kernel32.dll!BaseThreadInitThunk(unsigned long RunProcessInit, long(__stdcall*)(void *) StartAddress, void * Argument) Line 64	C
  ntdll.dll!__RtlUserThreadStart(long(__stdcall*)(void *) StartAddress, void * Argument) Line 1153	C
  ntdll.dll!_RtlUserThreadStart(long(__stdcall*)(void *) StartAddress, void * Argument) Line 1070	C

Notes

• This behavior starts showing with Boost 1.70.
  Earlier versions don't run into this bug.
• The bug happens only in the Release|x86 flavor, when using the NDEBUG preprocessor defintion.
  See Vc141Boost171.vcxproj.
• The bug does not happen when building with MSVC 14.2 (v142) nor 14.0 (v140).